Looping through a list of files to find those with the longest filenames requires a good understanding of how loops work and how blanks in filenames can complicate the required commands. LongFnameĤ1: Speeding up scripts using parallelization Running this script should look something like this: $. This regex works the same as 'lazer 0-9'. I would do it this way: ls egrep 'lazer :digit:'. Here, the files you want to list begin with lazer and are followed only by some digits (possibly more or less that 6). Longestname=`expr $sz - 1` # reduce by 1 for carriage return If you want a precise filter of your files, you must use regular expressions and hence use a command like egrep. Sz=`echo $file | wc -c` # get filename length It makes the inclusion of the newline very obvious. crash_files=(/var/log/crashes/**/app-*.You can see this issue more clearly by passing the same output to the od -bc command. (You can use head -c 1 if your head command supports it.)Īlternatively, use zsh. With other systems, pipe find into head to at least quit soon after the first match (find will die of a broken pipe). To find String Length in Bash Scripting use one of the following syntax. With GNU find (non-embedded Linux, Cygwin), use the -quit primary. Bash String Length In this tutorial, we will learn ways to find the length of a string in Bash Scripting. You should make find stop as soon as it finds a match, or soon after. This can potentially be inefficient: if there are many files in /var/log/crashes, find will explore them all. You don't need double quotes inside ] (though they don't hurt). In ksh, bash and zsh but not in ash, you can also use ] which has different parsing rules: ] is a different parsing construct. As always, use double quotes around the command substitution, otherwise the output of the find command will be broken into words, and here you'll get a syntax error if there is more than one matching file (and when there are no arguments, is true, whereas you want which is false). The only difference is their name, and the fact that as its last argument. The commands test and are exactly synonymous. Or if test -n "$(find /var/log/crashes -name app-\*\.log -mmin -5)" then You can do this by putting the output of find into a variable, and then using bashs test, to handle the different cases youre interested in. I also changed `command` to $(command), which also generally behaves similarly, but is nicer with nested commands. I have a directory with crash logs, and Id like to use a conditional statement in a bash script based on a find command. I've used ] in this example, as I do whenever possible. Otherwise it is generally the same as using. If you are using bash (and not sh), you can use ], which behaves more predictably when there are spaces or other special cases in your condition. n tests for a non-empty string: if ]Ī full list of test arguments is available by invoking help test at the bash commandline. However, all of the above examples only test against the program's exit status, and ignore the program's output.įor find, you will need to test if any output was generated. If /bin/rmdir then echo 'command succeeded' else echo 'command failed' fi # echoes "command failed" because rmdir requires an argument If /bin/echo hi then echo 'command succeeded' else echo 'command failed' fi This can actually be replaced by any program to check its exit status, where 0 indicates success and non-zero indicates failure: # echoes "command succeeded" because echo rarely fails Test returns a zero exit status if the condition is true, otherwise nonzero. Test -x /bin/cat & echo 'cat is executable' ), so you don't want to use & echo 'cat is executable'
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